Hydrocarbon oil conversion



May 5, 1936. L. c. HUFF HYDROCARBON OIL CONVERSION Filed Jan. 14, 1933 nOm Patented May 5,- 1936 PATENT OFFICE HYDROCARBON OIL CONVERSION LymanC. Hull, Chicago, vIll., sal'Oil Products Company,

poration of Delaware Application January 14, `1933, serial No. 651,741

(ol. 19e-'48) 6 Claims.

This invention particularly refers to an improved process and apparatusfor the simultaneous conversion of different hydrocarbon -oilchargingstocks wherein the different charging stocks and diiferentselected intermediate conversion products of the process are each sub-Vjected to independently controlled conversion conditions of elevatedtemperature and superatmospheric pressure regulated to secure theproduction of high yields of desirable light hydrocarbons such as motorfuel of high fantiknock value.

A specific embodiment of the present invention may comprise subjecting arelatively` low boiling hydrocarbon oil ,charging stock to conversiontemperature at superatmospheric pres. sure in a heating coil,introducing the heated oil into an enlarged reaction chamber, alsomaintained at superatmospheric pressure, withdrawing both vaporous andliquid conversion products from the reaction chamber to a reducedpressure vaporizing chamber wherein further vaporization of liquidconversion products rand separation of the residual liquid from thevaporous products of the process is accomplished, withdrawing residualAliquid from the vaporizing chamber and returning a regulated portionthereof to commingle with and assist cooling of the products passingfrom the reaction chambf-r to the vaporizing chambenwithdrawing vaporousconversion products from the vaporizing chamber and subjecting them toindirect contact and heat exchange with cooler oil from within the'system whereby a portion of their high-boiling components are condensed,subjecting the remaining vaporous conversion products to fractionation,supplying condensate resulting from said heat exchange in regulatedamounts either to the vaporizing chamber and/or to the frac-l tionatorand/or to the reaction chamber, arbitrarily separating the refluxcondensate formed by fractionation of the vaporous conversion productsinto low boiling and high boiling fractions, simultaneously supplying tothe fractionator, preferably in preheated state, another hydrocarbon oilcharging stock of different characteristics than the first mentionedcharging stock whereby it is subjected to the same separation in thefractionator as that afforded the vaporous conversion products of theprocess, subjecting fractionated vapors of the desired end-boiling pointto condensation, collecting the resulting distillate and gas, returningsaid lowboiling fraction of the reflux condensate, together with anycomponents of the second menof the process.

assignor to Univerv Chicago, Ill., a corinto the reaction chamber.

The first mentioned charging stock, which may, for the sake ofconvenience, be termed primary charging stock, preferably comprises ahydrocarbon oil distillate such as light gas oil, kerosene distillate,naphtha, pressure distillate bottoms, straight-run gasoline or othermotor fuel of inferior anti-knock value or fractions or mixtures of suchmaterials. The last mentioned or secondary charging stock, which issupplied to the fractionator of the system, may comprise any desiredhydrocarbon oil ranging from naphtha or other light distillates throughthe various crude oil fractions to residual or fuel oil and specificallyincluding oils such as crude petroleum, topped crudes and/the like, aswell as pressure distillate, pressure distillate bottoms or other finalor intermediate products of conversion. Any material boiling within therange of the desired nal light product of the process contained withinthe secondary charging stock are vaporized within the fractionator andrecovered with the motor fuel conversion product Any materials containedwithin the secondary charging stock boiling within the range or havingcracking characteristics similar to the primary charging stock arepreferably withdrawn from the fractionator, together with selectedlow-boiling fractions of the reux condensate of corresponding boilingrange and subjected to conversion, together withv the primary chargingstock. Any components of the secondary charging stock of higher `boilingnature than the material returned from the fractionator to conversionwith the pri- .mary charging stock collect with the high-boilingfractions of the refiux condensate and are subjected therewith toindependently controlled conversion conditions in a separate heatingcoil. Thus, it will be apparent that the process of the presentinvention possesses a wide flexibility with respect to the type of oilwhich may be employed as secondary charging stock, inherently providingfor (optimum treatment of the various fractions of virtually any type ofoil. y

' The accompanying diagrammatic drawing illustrates one specic form ofcracking apparatus embodying the features of the present invention andthe cooperative nature of its various features will be more apparentwith reference to the following description of the drawing whichincludes a more detailed description of the operation of the processasit may be practised in the apparatus shown.

Primary charging stock for the cracking operation which may comprise,for example, straightrun gasoline or other motor fuel of low-anti-knockvalue, naphtha, kerosene distillate, pressure distillate bottoms, gasoil, light gravity crude or similar hydrocarbon oil is supplied throughline I and valve 2 to pump 3 by means of which it is fed through line 4and valve 5 to heating coil 6. The charging stock may, of course, bepreheated in any well known manner (not shown) priorI to itsintroduction into the heating coil.

The oil supplied to heating coil 8 is subjected therein to the desiredconversion temperature, preferably at substantial superatmosphericpressure, by means of heat supplied from a furnace 'I of any suitableform. The heated oil is discharged from the heating coil through line 8and valve 9 into Vreaction chamber Ill.

Chamber III is also preferably maintained at a substantialsuperatmospheric pressure and, although not illustrated in the drawing,is preferably well insulated to prevent the excessive loss of heattherefrom by radiation so that conversion of the products introducedinto the reaction chamber, and particularly their vaporous components,may continue in` this zone. In the case here illustrated, both vaporousand liquid conversion products are withdrawnin commingled state from thelower portion of the reaction chamber, passing through line I I andvalve I2 into vaporizing chamber I3. When desired, in order to preventsegregation of vapors and gases in chamber III and the formation of agas pocket in the upper part of the chamber a portion of the vaporousconversion products may be separately withdrawn from the! upper portionof this zone passing through line 42 and valve 43 into chamber I3.

Chamber I3 is preferably maintained at a. substantially reduced pressurerelative to that employed in chamber I0, by means of which furthervaporization of the liquid conversion products introduced into this zoneis accomplished. The vaporous and residual conversion products of theprocess are separated in chamber I3 and the residual liquid remainingunvaporlzed in this zone is withdrawn therefrom through line I4 and maypass, all or in part, to storage or to any desired further treatmentthrough line I5 and valve I6.

When desired, in order to cool the products passing from chamber I0through line I I to chamber I3 further than the cooling accomplished bythe pressure reductionin passing through valve I2, so as to prevent theformation and deposition of coke or heavy pitch-like material in thisline fed through line I9 and valve 20 and through cool-l er 2I fromwhich it passes through line 22 and valve 23 into line II. When desired,all or any portion of the residual oil thus recirculated to line I I mayby-pass cooler 2| by means of line 24, controlled by valve 25.

Vaporous products of the process are withdrawn from chamber I3 throughline 26 and valve 21 and may pass throughheat exchangers 28 and 29, aconnecting vapor line 30 being interposed between the heat exchangers,passing therefrom through line 3| and Valve 32 to fractionation infractionator 33.

The vaporous conversion products of the process 4are partially cooled inheat exchangers V28 and 29 by indirect contact with a suitable coolingmedium, preferably comprising raw oil charging stock or intermediateconversion products of the process or mixtures of such materials,whereby the heat extracted from the vapors is recovered for a usefulpurpose and certain high-boiling fractions of the vapors, undesirable asrecycled stock, are condensed therefrom. Condensate formed in heatexchangers 28 and 29 is withdrawn therefrom through line 34 and valves35, respectively, con'- trolled by the respective valves 36 and 31,passing into line 38 from which all or a portion of this material may bereturned through valve 39 in this line into vaporizing chamber I3 orthrough valve 40, in line 38, into fractionator 33. A valve 4I, in line38, between the junction of this line with lines 34 and 35 permitsseparation of the condensates from heat exchangers 28 and 29 so that thesomewhat heavier material from the first heat exchanger 28, may beturned to chamber I3, as described, while the somewhat lightercondensate from the second heat exchanger 29, passes to chamber 33. Inthis manner when substantially all of the objectionable heavy componentsof the vapors are condensed therefrom in heat exchanger 28, additionalheat may be extracted from the vapors in heat exchanger 29, prior totheir fractionation for the preheating, for example, of raw oil orrecycled stock without decreasing the desirable recycled stock which, inthis case, is returned from heat exchanger 29 to fractionator I33. Itwill be understood that itis within the scope of the invention to employa single heat exchanger or any number of a plurality of such zones,dividing the condensate therefrom, when desired, into any number ofseparate streams of somewhat different boiling characteristics fortreatment in the manners indicated.

Ordinarily, rough fractionating means such'as suitable baffles (notshown) are located in the upper lportion of vaporizing chamber ,I3 forthe purpose of preventing heavy oil particles entrained in the vaporsfrom passing to further treatment therewith. In such cases thecondensate returned from heat exchanger 28 or from heat exchangers 28and 29 to chamber I3 will serve as a refluxing medium, being introducedabove the fractionating means and flowing downward thereover to assistcooling of the vapors and extraction of the entrained heavy oilparticles.

The vaporous conversion products of the process supplied to fractionator33, as described, are subjected to fractionation in this zone by wellknown means whereby their insufficiently converted components, boilingabove the range of thel desired ilnal lightv distillate product of theprocess, are condensed as reflux condensate.

Fractionated vapors of the desired end-boiling point, representing thenal light distillate product of the process and preferably ofsubstantially motor fuel boiling range, are withdrawn, together withuncondensable gas, from the upper portion of fractionator 33 throughline 58 and valve 5I to be subjected to condensation and cooling incondenser 52, from which the resulting distillate and gas passes-throughline 53 and-va1ve 54 to collection and separation in receiver 55.Uncondensable gas may be released from the receiver through line 56 andvalve 51. The distillate may be withdrawn from receiver 55 through line58 and valve 59 to storage or to any desired further treatment. Whendesired, a'portion of the distillate collected in receiver 55 may berecirculated, by well known means (not shown) to the upper portion offractionator 33 to assist fractionation of the vaporsin this zone and tomaintain the desired vapor outlet temper- Y' ature from thefractionator..

As a special feature of the invention the reflux f condensate formed infractionator 33 is arbitrarily separated into low-boiling andhigh-boiling fractions. The low-boilingA fractions of the refluxcondensate are withdrawn as a `side-stream from one or a plurality vofsuitable .points in the fractionator, for example, through lines 44,controlled by valves 45, passing through line 46 to pump 41 by means ofwhichv this relatively .low`

boiling oil, preferably within the boiling range or otherwisecorresponding in cracking characteristics to the primary charging stock,is fed through line 48 and valve 49 into line 4, commingling therein.with the primary charging stock` and passing therewith to conversion inheating coil 6. It will be understood that well known means (not shown)may be provided,I when desired, for subjecting the side-stream fromfractionator 33 to reboiling, whereby it may be substantially freed ofdesirable light products within the boiling range of the overheadproduct from the fractionator.

Heavy fractions of the reflux condensate formed in fractionator 33,boiling above the desired end-boilingpoint of the selected fractionsreturned to heating coil 6 as described, collect within the lowerportion of the fractionator, from which they are withdrawn through line68 andv valve 6I to pump 6.2,by means of which they are returned throughline 63, valve 64, heat exchanger 29, line 65, heat exchanger 28, line66 and valve 61 to heating coil 68 for further conversion. -It will beunderstood that, when desired, all or any portion of this material maybe diverted from either or both of the heat exchangers, by well knownmeans (not shown).

The oil supplied to heating coil 68 is subjected therein toindependently controlled conversion conditions of elevated temperatureand superatmospheric pressure by means of heat supplied from a furnace69 of any suitable form and the heated oil is discharged through line 18and valve 1 I 'into' reaction chamber I8, commingling therein or priorto its introduction thereto with the heated oil from heating coil 6, andbeing subjected thereafter to the same treatment, in chamber I8 and insubsequent portions of the system, as that already described inconnection with the heated oil from heating coil 6.

As another special feature of the invention a suitable oilor mixture ofoils, preferably from within the system, may be introduced, at one or aplurality of desirable points, into reaction chamber I8, particularlyfor the purpose of cooling and/or diluting and increasing the volume ofliquid traversing or withdrawn from this zone. Such an oil, introduced,for example, into the upaosavsv shown).

described comprises a portion of the high-boiling 2 per portion ofchamber I8 through line 12 and valve 13, may be sprayed against theinner surfacevof the walls of the reaction chamber by any suitable spraydevice (not shown), to dilute, cool and increase the volume of liquidpassing downward over the walls of the chamber in order to hasten itspassage through and removal from this zone, thereby assisting inpreventing the formation of coke on the walls of the chamber. In asimilar manner oil introduced into the lower portion of the chamberthrough line 14 and valve 15 may commingle with the vaporous and liquidconversion products withdrawn through line Il,

\ thereby increasing the volume of liquidpassing rial in line I I. i(The drawing illustrates a method and means of employing two specificintermediate products of the operation as'cooling oil in chamber I8. Onesuitable material for this purpose comprises all or' a portion of thecondensate from heat exchangerv 28 or from heat exchangers 28 and 29which iswithdrawn from line 38 through line 16 and valve 11 to pump 18by means of which it is fed through line 19, valve 88 and cooler 8|,passing therefrom, after being cooled to any desired degree, throughline 82, valve 83 and line 84 into chamber I8, entering this zone eitherthrough line 12 or through line 14,I as previously described, or at anyother desired point vin the chamber (not Another suitable oil for thepurpose fractions of the reflux condensate withdrawn from the lowerportion of fractionator 33 including in some cases, as will be latermore fully described, secondary charging stock or high-boiling fractionsthereof supplied to fractionator 33. This oil may be diverted from line68 through line 86 and valve 81 and through line 16 to pump 18 to be fedtherefrom, either alone or together with condensate from line 38, tochamber I8, as previously described. When desired, a portion or all ofthe oil thus recirculated to chamber I8 may by-pass cooler 8| by meansof valve 85, in line 84.

Simultaneous with the operation already described, a secondary chargingstock comprising any desired oil, ranging, as already ind'cated, frominto fractionator 33, entering this zone at any desired point. Heatexchanger 93 offers a means of preheating the secondary charging stockby means of heat recoveredfrom the fractionated vaporous products of theprocess, prior to their introduction into condenser 52. and prior to theintroduction of the secondary charging stock into the fractionator. Itwill be understood that the secondary charging stock may, when desired,be supplied to the fractionator without preheating or that it may bepreheated to any desired degree in any well known manner (not shown).The secondary charging stock thus supplied to fractionator 33 issubjected to vaporization in this zone by direct contact and heatexchange'with the vaporous conversion products of the process unarevaporized within the fractionator, withdrawn therefrom, subjected tocondensation and collected together with the distillate resulting fromconversion. Higher boiling fractions of the secl ond-ary charging stockcorresponding in boiling range to the low-boiling fractions of thereflux condensate, returned, as described, to heating coil 6, arecollected therewith and subjected to the same treatment. When thesecondary charging stock contains any appreciable fractions of higherboiling point than the side-stream supplied to heating coil 6 theycollect, together with the high boiling fractions of the refluxcondensate, in the lower portion of fractionating column 33 and arereturned therewith to further conversion in heating coil 68.

The primary charging stock and selected lowboiling side stream from theyfractionator are preferably subjected to a temperature ranging from 950to 1050 F., at a superatmospheric pressure of from 300 to 800 pounds, orthereabouts, per square inch, measured at the outlet from the heatingcoil to which they are supplied. The high-boiling fractions of theintermediate conversion products, together with any correspondingfractions of the secondary charging stock, are preferably subjected to atemperature within the range of 850 to 975 F., at a superatmosphericpressure of from 100 to 500 pounds, or more, per square inch, measuredat the outlet from the separate heating coil to which this material issupplied. A The pressure employed in the reaction chamber may range, forexample, from 100 to 500 pounds, or thereabouts per square inch, andpreferably is substantially equalized with the pressure at the outletfrom the heating coil employing the lowest pressure, in case differentpressures are employed in the two heating coils. A reduced pressureranging, for example, from 100 pounds, or thereabouts, per square inch,down to substantially atmospheric pressure is preferred in thevaporizing chamber and the pressures employed in the succeedingfractionating, condensing and collecting portions of the system may besubstantially equalized "with or somewhat reduced relative to thepressure employed in they vaporizing chamber.

ble operations of the process of the present inventon, the primarycharging stock, which amounts to about 56% of the total oil subjected toconversion in the process, is a 45 A. P. I. gravity naphtha having aboiling range of approximately 265 to 470 F., with an octane num-v berof approximately 35, a sulphur content of about 0.41% and containingabout 77% of material boiling up to 400 F. with an octane number ofapproximately 43. The secondary charging stock is pressure distillatederived from other cracking operations containing about 75% of 400"yend-point motor fuel having an octane number of approximately 73 and asulfur content of about 0.25%. The 25% or thereabouts of material in thesecondary charging stock, boiling above 400 F. comprises about 44% ofthe total oil subjected to conversion in the system, the motor fuelcomponents of the secondary charging stock being recovered, Withoutconversion, together with the motor fuel product of the process, as anoverhead stream from the fractionator. Components of the secondarycharging stock and intermediate conversion products of the processhaving an end-boiling point of approximately 650 F. are withdrawn as aside stream from the fractionator and subjected to conversion, togetherwith the As a specific example of one of the many possli ancona? primarycharging stock, at a temperature of from 970 to 980 F. measured at the.outlet from the heating coil. The higher boiling components of thereflux condensate are subjected in a separate heating coil to aconversion temperature of 930 to 935 F. Pressures in excess of 1,000pounds per square inch are maintained at the vinlet to both heatingcoils and a pressure of approximately .400 pounds per square inch ismaintained in the reaction chamber.v The pressure is reduced in .thevaporizing chamber to about 85 pounds per square inch and issubstantially equalized in the succeeding fractionating, condensing andcollecting portions of the system. 'I'his operation may yield, perbarrel of total charging stock, neglecting the 75% or thereabouts ofmotor fuel inthe secondary charging stock which is not subjected.

to conversion, about 77% of 400 F. end-point motor fuel having an octanenumber of about 'l2 and a sulphur content of approximately 0.23%,

the additional products of the process being about of low gravityresidual oil having a velocity of about 12 seconds Saybolt Furol at 122F. and

containing about 0.5% B. S. and W. and about 430 due, passing suchseparated vapors to a fractionating zone and fractionatng the sametherein in direct contact with the heavier charging oil therebycommingling the latter with the reflux condensate formed by thefractionation, separating the commingled charging oil and reux duringthe fractionation into relatively light and heavy liquid fractions,passing such heavy liquid fraction through a heating zone maintained atcracking temperature and thence dischargmgthe same into the reactionzone, at least a portion of said A*heavy liquid fraction supplied t0said heating zone `being passed in indirect heat exchange with thevapors being supplied from said separating zone to the fractionatingzone and resultant condensate being introduced to the separating zone,combinmg said light liquid fraction with the lighter charging oil,passing the resultant mixture through a second dheating zone maintainedat higher cracking temperature than the first-mentioned heating zone andthence introducing the same to the reaction zone, and finally condensingthe vapors uncondensed in the fractionatl-ng zone.

2. A process for the simultaneous cracking of relatively light and heavycharging oils which comprises maintaining hydrocarbon oil under crackingconditions of temperature and pressure in a reaction zone, removingvapors and unvaporized oil as a mixture from said zone, lowering thepressure on said mixture and separating the same in a separating zoneinto vapors and residue, passing such separated vapors to afractionating zone and fractionating the same therein in direct contactwith the heavier charging oil thereby commingling the latter with thereflux condensate formed by the fractionation, separating the commingledcharging oil and reflux during the fractionation into relatively lightand heavy liquid fractions, passing such heavy liquid fraction through aheating zone maintained at cracking temperature and thence dischargingthe same into the reaction zone, at least a portion of said heavy liquidfraction supplied to said heating zone being passed in indirect heatexchange with the vapors being supplied from said separating zone to thefractionating zone and resultant condensate being introduced to the.reaction zone, combining said light liquid` fraction'with the lighter.charging oil, passing the resultant'mixture through a second heatingzone maintained at higher cracking Atemperature than the firstmentionedheating zone and thence introducing the same to the reaction zone, andnally condensing the vapors uncondensed in the fractionating zone. f

3. A conversion process which comprises subjecting hydrocarbon oil tocracking conditions of temperature and pressure in a cracking zone,removing vapors and unvaporized oil as a mixture from said zone,lowering the pressure on said mixture and separating the same in aseparating zone into vapors and residue, passing such separated vaporsto a fractionating zone and fractionating the same therein in directcontact with charging oil for the process, passing admixed charging oiland reiiux condensate from the fractionating zone in indirect heatexchange relationfwith the vapors being supplied from the separatingzone to the fractionating zone and then introducing the same to thecracking zone, introducing condensate formed by said heat exchange tothe separating zone, and finally condensing the fractionated vapors.

4. A conversion process which comprises subjecting hydrocarbon oil tocracking conditions of temperature and pressure in a heating coil andreaction zone, removing vapors and unvaporized oil as a mixture fromsaid zone, lowering the pressure on said mixture and separating the samein a separating zone into vapors and residue1 passing such separatedvapors'to a fractionating zone and fractionating the same therein indirect contact with charging oil for the process, passing admixedcharging oil and reiiuxcondensate from the fractionating zone inindirect heat exchange y relation with the vapors being supplied fromthe separating zoner to the frationating zone and then introducing thesame' to the heating coil,

introducing condensate formed by said heat ex-` change to the separatingzone, and nally condensing the fractionated vapors.

5. The process-as defined in claim 4 further k characterized in thatcondensate formed by said heat exchange is also introduced to thereaction zone.

6. A conversion process which comprises subjecting hydrocarbon oil to'cracking conditions of temperature and pressure in a heating coil andreaction zone, removing vapors and unvaporized oil as a mixture fromsaid zone, lowering the pressure on said mixture and separating the samein a separating zone into vapors and residue, passing such separatedvapors to a fractional-,ing zone and fractionating the same therein indirect contact with charging oil for the process, passing admixedcharging oil and reux condensate from the fractionating zone in indirectheat exchange relation with the vapors being supplied from theseparating zone to the fractionating zone 'and then introducing the sameto the heating coil, introducing condensate formed by said heat exchangeto the reaction zone, and nally condensing the fractionated vapors.

4L YMAN C. HUFF.

